The invention relates to a universal extractor for total endoprostheses of the knee joint according to the species of the claims.
Only a few extractors and clamping devices are currently available; their mechanism is often not useful.
Thanks to the improvement made in the design of prostheses, the TEP of knee joints have reached almost the same importance as the ones of hip joints. But also the number of exchange operations is continuously increasing. The basic problems of such TEP can be compared with the ones combined with hip joint prostheses.
About 20 years ago the market of total endoprostheses was dominated by cemented, coupled prosthetic components provided with a shaft. If they loosened or infections developed, serious osseous defect situations were often caused. Usually, such prostheses could be removed without any problems. In case of persistent infections, an amputation was not uncommon.
In the period following, the uncoupled, mostly cement-free surface replacement prostheses that had several advantages took over the market.
If revision surgery is necessary, the removal of such prostheses is not unproblematic. But also here, in case of revision only a few technical solutions are available that allow the extraction of an implant without causing damage to the bones.
The few useful extractors for knee prosthetic components have the disadvantage that they do not allow a stable friction-fit anchoring at said components. Also the sledge hammers produce only an unsatisfactory power transmission during the explantation of the joint components.
In case of revision surgery, the rigid osseous integrated cement-free, more seldom also cemented, components must be “pre-loosened” by means of diverse tools. The object is to reduce the anchoring surface area of the prostheses and thus the shearing forces acting during the explantation. This is the only way to avoid secondary injuries for the osseous bed around the prosthesis or disadvantageous osteotomities and thus to facilitate the reimplantation of a revision prosthesis.